Engine mass-flow rate coupling for zero-thrust simulation

[m-minervino]

Added flag to allow mass-flow rate coupling between all exhaust boundaries towards the engine inlet.

Proposed Changes

When simulating a turbofan engine in idle regime (no thrust), total free-stream conditions can be imposed at fan and core exhaust boundaries (i.e. no energy variation by the engine), but no information is usually available at the fan inlet boundary (for example, the target mass-flow rate to be used).
Assuming that both engine bleed and fuel addition are negligible, the sum of mass-flow rates computed at all exhaust boundaries can be specified as a target for the inlet (ENGINE_INFLOW_TYPE= FAN_FACE_MDOT).
The proposed modification, then, changes the target value at run-time (instead of using a fixed pre-defined value specified in the configuration file) to match the overall outlet mass-flow rates.

by: Angelo Passariello and Mauro Minervino (Italian Aerospace Research Centre).

Related Work

None.

PR Checklist

• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with --warnlevel=3 when using meson).
• My contribution is commented and consistent with SU2 style (https://su2code.github.io/docs_v7/Style-Guide/).
• I used the pre-commit hook to prevent dirty commits and used pre-commit run --all to format old commits.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp), if necessary.

[pcarruscag]

Can you add a test? The engine features are not covered very well.

[m-minervino]

Dear Pedro,

we just uploaded the .cfg file for the test-case, but the compressed mesh file is too large to be uploaded on the SU2 test-cases repository (76MB). Is there another way to upload the mesh?

Kind Regards,
Angelo and Mauro

[pcarruscag]

We use the testcases repo for meshes, but that is pretty large even by those standards.
Can you create a simpler case? Or coarser mesh.

[m-minervino]

I understand. Just uploaded a coarser mesh in the testcases repo. Please let us know if you need additional input.

[pcarruscag]

Yes, please modify parallel_regression.py to add your test so that it runs in the github actions and set suitable regression values

[m-minervino]

ok, done.

[bigfooted]

In .github/workflows/regression.yml you can change this line to point to the testcase branch m-minervino:develop :
# -t -c
args: -b ${{github.ref}} -t develop -c develop -s ${{matrix.testscript}}

Else it cannot find the mesh since it is not in develop yet.

[m-minervino]

I just modified the file, hope in the correct way.

[pcarruscag]

update

[pcarruscag]

You are listing things here that don't exist anymore

Suggested change

	% Solver type (EULER, NAVIER_STOKES, RANS,
	% INC_EULER, INC_NAVIER_STOKES, INC_RANS,
	% NEMO_EULER, NEMO_NAVIER_STOKES,
	% FEM_EULER, FEM_NAVIER_STOKES, FEM_RANS, FEM_LES,
	% HEAT_EQUATION_FVM, ELASTICITY)

[pcarruscag]

Suggested change

	% Specify versions/corrections of the SST model (V2003m, V1994m, VORTICITY, KATO_LAUNDER, UQ, SUSTAINING)
	SST_OPTIONS= V2003m
	%
	% Specify versions/corrections of the SA model (NEGATIVE, EDWARDS, WITHFT2, QCR2000, COMPRESSIBILITY, ROTATION, BCM, EXPERIMENTAL)
	SA_OPTIONS= NEGATIVE, WITHFT2
	%
	% Specify subgrid scale model(NONE, IMPLICIT_LES, SMAGORINSKY, WALE, VREMAN)
	KIND_SGS_MODEL= NONE
	%
	% Specify the verification solution(NO_VERIFICATION_SOLUTION, INVISCID_VORTEX,
	% RINGLEB, NS_UNIT_QUAD, TAYLOR_GREEN_VORTEX,
	% MMS_NS_UNIT_QUAD, MMS_NS_UNIT_QUAD_WALL_BC,
	% MMS_NS_TWO_HALF_CIRCLES, MMS_NS_TWO_HALF_SPHERES,
	% MMS_INC_EULER, MMS_INC_NS, INC_TAYLOR_GREEN_VORTEX,
	% USER_DEFINED_SOLUTION)
	KIND_VERIFICATION_SOLUTION= NO_VERIFICATION_SOLUTION
	%
	% Mathematical problem (DIRECT, CONTINUOUS_ADJOINT, DISCRETE_ADJOINT)
	MATH_PROBLEM= DIRECT
	%
	% Axisymmetric simulation, only compressible flows (NO, YES)
	AXISYMMETRIC= NO
	%
	% Restart solution (NO, YES)
	RESTART_SOL= NO
	%
	% Discard the data storaged in the solution and geometry files
	% e.g. AOA, dCL/dAoA, dCD/dCL, iter, etc.
	% Note that AoA in the solution and geometry files is critical
	% to aero design using AoA as a variable. (NO, YES)
	DISCARD_INFILES= YES
	%
	% System of measurements (SI, US)
	% International system of units (SI): ( meters, kilograms, Kelvins,
	% Newtons = kg m/s^2, Pascals = N/m^2,
	% Density = kg/m^3, Speed = m/s,
	% Equiv. Area = m^2 )
	% United States customary units (US): ( inches, slug, Rankines, lbf = slug ft/s^2,
	% psf = lbf/ft^2, Density = slug/ft^3,
	% Speed = ft/s, Equiv. Area = ft^2 )
	SYSTEM_MEASUREMENTS= SI
	%

[pcarruscag]

Suggested change

	% Critical Temperature (131.00 K by default)
	CRITICAL_TEMPERATURE= 131.00
	%
	% Critical Pressure (3588550.0 N/m^2 by default)
	CRITICAL_PRESSURE= 3588550.0
	%
	% Acentri factor (0.035 (air))
	ACENTRIC_FACTOR= 0.035
	%

[pcarruscag]

This file is full of irrelevant options. Please take a look at our other configs and make this one look similar.

Suggested change

	% Temperature polynomial coefficients (up to quartic) for specific heat Cp.
	% Format -> Cp(T) : b0 + b1*T + b2*T^2 + b3*T^3 + b4*T^4
	CP_POLYCOEFFS= (0.0, 0.0, 0.0, 0.0, 0.0)